In automatic transmission systems, torque is transmitted from component to component within the transmission by a torque transmitting assembly. Frequently, torque transmitting assemblies are of complex design, permitting them to serve several functions and reduce the number of components in the transmission system. In such a case, the materials from which the torque transmitting assembly is made is usually selected to accommodate the greatest stresses applied to this complex torque transmitting assembly. A large portion of the torque transmitting assembly is typically stronger and heavier than is really necessary for the application.
In order to reduce weight, aluminum is used in place of steel where possible. Aluminum is not an appropriate material for such components as annulus gears, but it can be used for drive shells or drums which transmit the torque between annulus gears and other supporting or torque-controlling structures within the transmission. The drums are can be formed from a flow forming process. An example of such an assembly and method of forming is shown and described in U.S. Pat. Nos. 7,021,171 and 7,328,492, the disclosures of which are hereby incorporated herein by reference in their entirety.
However, this is a continual need to minimize a weight, a cost, and complexity of the torque transmitting assemblies. Additionally, it is desired to maximize a rigidity and an efficiency of the torque transmitting assembly with enhanced interlocking and coupling of the components.